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Yang H.-B.,China University of Petroleum - Beijing | Zhang Q.-D.,Petrochina | Liu N.,Petrochina | Liu N.,National Engineering Laboratory of Low Permeability Oil | Wei X.-L.,China National Petroleum Corporation
Oilfield Chemistry | Year: 2013

Aimed at the low temperature and high salinity condition of low permeability fractured reservoir in GY oilfield, the crosslinker JL-1 was synthesized by three chromium chloride, sodium hydroxide, acetic acid and daucic acid. Then with gelling time and gel strength as evaluation indexes, a weak gel profile control system KY-1 in low temperature and high salinity reservoirs was prepared by regulating the relative molecular mass of polymer(HPAM)and the concentration of HPAM and JL-1. The performance of salt tolerance and shear resistance of KY-1 was investigated, and the plugging capacity and oil displacement efficiency of KY-1 was estimated. The results showed that the best formula of KY-1 weak gel flooding system which was applied to GY oilfield was: T114 oil formation water, 3000 mg/L HPAM(M=1400×104)and 500 mg/L JL-1. When the salinity of formation water was 40 g/L, the weak gel system could gelatinize rapidly in 60 hrs with 30 Pa·s gel strength and good salt tolerance. The system also had good sheering tolerance. The gel strength of system was 25600 mPa·s and the gel viscosity loss rate was 18.99% after 120 min sheering at 200 s-1, 27°c. The stemming ratio of fractured cores in average was 88.7%, and average enhanced oil recovery rate was 12.1%. Source

Zheng L.-J.,Petrochina | Zheng L.-J.,National Engineering Laboratory of Low Permeability Oil | Guo F.-Y.,Petrochina | Guo F.-Y.,National Engineering Laboratory of Low Permeability Oil | And 4 more authors.
Oilfield Chemistry | Year: 2013

According to the plugging difficulty in fractured reservoir of Wangyao infilled block, the urea-formaldehyde resin plugging agent with high strength was synthesized by formaldehyde and carbamide at 55°C, and its performance was studied. The results showed that the dissolution rate in injected water, paraffin and mixed acid (10% HCl+3% HF) was 1.54%, 2.40% and 14.30%, respectively. Its hydrotrope, oil and acid soluble were all lower which indicated good stability. With increasing temperature, the curing time of urea-formaldehyde resin shortened, and its compressive resistance increased fast. The curing time was 10 h, and the compressive resistance was 12.2 MPa at 55°C. With increasing degree of mineralization, the compressive resistance decreased and the curing time extended. The curing time was 12 h, and the compressive resistance was 4 MPa when the degree of mineralization was 50 g/L. The plugging efficiency in fractured reservoir was higher than 95%, and the breakthrough pressure was more than 24 MPa which showed high plugging off intensity. The "weak gel and urea-formaldehyde resin" system was applied for field construction in converted injector well Wang19-06. Cumulative quantity of oil was 545.56 t, water cut decrease was 475.92 m3, and valid period was more than 10 months. The pilot effects of increasing oil production and decreasing water cut were good. Source

Du Z.-F.,National Engineering Laboratory of Low Permeability Oil | Du Z.-F.,Petrochina | Li W.-H.,National Engineering Laboratory of Low Permeability Oil | Li W.-H.,Petrochina | And 8 more authors.
Oilfield Chemistry | Year: 2010

Based on the analysis of the geological features and fluid properties of the Triassic reservoir in Gao 52, the feasibility of associated gas miscible flooding was evaluated by the flooding experiment and the calculation of minimum miscibility pressure. The minimum miscibility pressure calculated was of 15.11 MPa, which was greater than the initial formation pressure ( 13.05 MPa). Therefore, the reservoir could be developed by the associated gas immiscible oil displacement rather than by the miscibility of associated gas. The oil displacement effects of different associated gas slug and the single-well gas injection volume in different injection-production ratio were studied. The experiment results showed that oil displacement efficiency of water flooding was of 42.5% and that of associated gas flooding was of 53.3% , increasing by 10.8%. The gas injection volume and the wellhead pressure of injection well calculated were of 8784 m3/d and 8. 89 MPa, respectively, which could satisfy the field application in the injection-production ratio of 1.2. Source

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